Radio tuning system



RADIO TUNING SYSTEM Filed May 22, 1946 FIG.|

. INVENTOR JOSEPH WEINGARTEN ATTORNEY Patented June 20, 1950 RADIO TUNING SYSTEM Joseph Weingarten, United States Navy,

New York, N.Y.

Application May 22, 1946, Serial No. 671,486

8 Claims. (Cl; 250--16) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) .This invention relates in general to a novel :electronic scale index, and more particularly to -a tuning system incorporating an electron ray tube indicator and a calibrated scale, indicator and scale being relatively movable.

The electron'ray tube, also known as the magic eye or tuning eye comprises essentially, a central cathode structure common to a circular,

fluorescent target or indicator electrode and a triode amplifier. A rod-like ray control electrode is disposed between the cathode and the target electrode, and is directly connected to the triode plate. Consequently, the relative potential of the ray control electrode is a function of thev control potential applied to the triode grid. Those electrons emitted from the cathode which strike the target electrode cause it to fluoresce and provide a luminous area. The extent of this luminous area isgoverned by the ray control electrode potential relative to the target potential, and innormal operation the ray control electrode produces an angular shadow upon the illuminated fluorescent screen. The shadow angle 'is :a function of the instantaneous triode grid control potential.

Electron ray tubes are particularly inexpensive devices, and are in wide use as visual indicators in electrical equipment. In radio, the principal application is a visual indicator of the accuracy of tuning. For this purpose, the electron ray tube is connected into the radio circuit such that the negative automatic volume control (AVC) bias is applied as a control potential to the triode section grid. As the-radio is tuned to a signal, the AVG bias becomes stronger and the electron ray shadow angle decreases (the eye closes). The shadow angle is at a minimum when tuning is most accurate; that is, when the strength of the received signal is a maximum.

In prior radio tuning systems, the arrangement of the electron ray tube was substantially independent oi. the means for indicating the frequency of the received signal. Generally, the physical separation between the pointer indicating signal frequency on a calibrated scale and the electron ray tube made it inconvenientto follow simultaneously both pointer and the changes in tube shadow angle when tuning to a desired signal.

The present invention contemplates and has as a primary object the utilization of an electron ray tube as a scale index, the scale and tube being relatively movable.

Another object of the present invention is to provide a radio scale index which provides an in- 2 dication of the accuracy of tuning to a receive signal.

A further object-of the present invention is to provide a tuning system wherein the vertex of the angular shadow presented by an electron ray tube is utilized as an index for a scale.

These and other objects of the present invention will now become apparent from the following detailed specification when taken in connection with the accompanying drawings in which,

Fig. 1 is a general perspective view of a radio incorporating novel tuning principles,

Fig. 2 is a broken perspective view of one possible embodiment of the tuning apparatus as sociated with the radio of Fig. 1,

Fig.3 is a fragmentary perspective view of an alternate tuning apparatus, and

Fig. 4 is an exploded perspective view illustrating an electron ray tube and an index shield therefor.

Referring now to the drawings and more particularly to Figs. 1 and '2, there is illustrated a table model radio Ill which comprises essentially an enclosure or cabinet I I of suitable design, having a plurality of conventional controls, such astuning control I2,-associated therewith. All

details specific tocircuit design and construction have been omitted from the drawings, inasmuch as these are not essential to an understanding of the present invention.

Associated with radio III is an opaque scale I3, printed or otherwise marked upon a transparent strip I8, suitably secured to cabinet I!. Scale I3 is calibrated in terms of frequency, and covers the frequency band receivable by rotation of tuning control I2. I

An electronic scale index comprising an electron ray tube I4, of the type hereinabove described, is disposed within cabinet II behind transparent strip I8, and is oriented so that the wedge-shaped shadow I5 appearing on the fluorescent target electrode thereof is visible from the front of radio Ill. As best illustrated in Fig. 1, the vertex I6 of the angular shadow I5 appears substantially in contact with the upper edge of scale I3.

As illustrated in Fig. 2, electron ray tube I I is movable relative to scale I 3. Thus, tube I 4 is secured within a tube socket 22, which in turn is supported upon a carriage 23. Socket 22 is preferably rotatable so that the angular shadow I5 may be aligned as shown in Fig. 1 subsequent to installation of tube I4. Carriage 23 slidab1y engages a pair of parallel rails 2 I, fixed to the radio cabinet II in a suitable manner and is in addition attached by means not illustrated to and endless, taut string 2'! which extends about two freely rotatable pulleys 3| and 32, the latter bein supported within the radio cabinet I I upon shafts 33 and 34 respectively. String 2'! is looped around a small pulley 35 secured to shaft .35 extendin from the tuning control l2. An extension of shaft 36 (not shown) is utilized to drive the frequency tuning system, ordinarily in the form (of variable capacitors or inductors, of radio l0.

Electron ray tube M is energized from thecircult of radio Hi over multi-comluctor, flexible cable 25 extending from the base of tube socket 22. In addition to heater currents. tube I 4 is supplied with triode plate potential, andtri'ode'gri'd potential. tential is obtained from the radio AVC circuit, and is a negative maximum when radio ll] is accurately tuned to an incoming signal. -Under these circumstances the angle of shadow I5 is a :minimum.

Thus, from consideration of Figs. 1 and 2 it is evident that the rotation of tuningcontrol l2 will drive electron lray tube I 4 and its associated carriage along rails zlgparallel to frequency calibrated tuning scale I3,while-simultaneousl tuning radio '1 i! over the frequency bantl for which it hasbeendesign'ed. the frequency bandiscov- -ere'd, each receivedsignalgby afiec'ting the aforementioned AVG circuit, causes "the angle of shadow 15 to decrease to a minimum. The angle of shadow 15 increases as radio =m 'i's detuned. "If the band covered includes a'num'ber'of signals, the angle of shadow 15 will alternately close and open as tuning rc'ontrol i2 is rotated.

In accordance with "the principles of this invention, electron ray tube l lppos'itioned as illustrated, "provides a readily visible, convenient in- Idexeforthe markings of scale 13. while tube l4 traverses rails 2!, vertex E5 of angular shadow i 'l5-clearly indicates the frequency to which radio I U is tuned, and such indication is substantially independent 'of variations in ang'le caused by corresponding AVG "signal intensity variations. In

frequency is known. control 12 is rotated in that direction which drives lecti'on ray tube 14 'toward the desired frequency asindicatedon scale i3. Observation of the angular shadow f5 and the scale markings adjacent vertexl'tisimultaneously 'provides indications of station frequency and accuracy oftuningth ereto.

Although radio H! as illustratedin Figs. 1 and2 is representative of "a 'type'primarily "suited for homeuse, the-electron ray tubescale'index-shown may be employed equally well in connection with "com'muriicatiori type 'radios'and other tunable electronic apparatus. In such'applications-scale readings are often required with a high degree of precision. 'Accor'dinglyasharply defined index line 3! (Fig. '1) has been marked on theface of electron ray tube l4,"-bisecting the angle of shadow l5. Index line 31 ispositioned in this 'manner by suitable test,'and may extend diametricallyacross theface'of thetube. In operation, rough frequenc indications are obtained by use of the tube M as described :above, and precise readings are obtained'by careful observation of index line .31 and scale l3, It will be understood .that fora radio as shown in"Figs..1.and 2,,index line 3'3 is optional.

The general principles .of apparatus .using an electron ray tubeniovable .relative to scale need not beapplied solely to the straight .scale illustrated in Figs. 1 andz. Thus, the electron ray For tuning indications the llatter;p.o-,

tuning "to a particular radio station'where the tube index may, by simple mechanical design be altered to traverse a path parallel to an adjacent cooperating scale of any desired configuration. As an example, the electron ray tube may be supported at the end of a pivoted arm, thereby providing an index for a fixed, circular tuning scale, while simultaneously providing tuning indications.

Fig, 3 is a representationof the elements of a radio tuning system utilizing an electron ray tube scale index, wherein the electron ray tube is fixed to the firame of the radio apparatus and the scale movable relative thereto. For clarity, elements 'of .Eig. 3 corresponding to elements described in connection with Figs. 1 and 2, have been similarly designated. Thus, electron ray tube I4 is suppolited behind an escutcheon plate 39 within a socket 4 l, the latter preferably being rotatably secured tby means :not shown) to the radio cabinet "or chassis. Electron ray tube M is energized by multi-conductor cable M connected to the radio circuit for tuning accuracy indications :as describe-dabove forz-Eigs l andzz. -When energized tube M :presents a variablezangle shadow :lt5, the vertex lii of which 'is oriented, "by :rotation of socket M, to serve'as .aniindexzfor :a'rotatable arcuate scale vii-l. :Scale Hi3 is afastenedyby means of "cross-arm M, to :a irotatable shaft M extending from-tuning contmlflfi. The-radio tuning :means, diagrammatically represented by rotatable .capacitor plates dii, are salsossecured to shaft 4'4.

As is evident from Fig. 2-3, :thesselection of -:a desired radio stationiis accomplished'byutilizingthe vertex 5H5 .Of :angu'lar shaped shadow I 5 as an .iindexfor: adj acentssc ale 43 while simultaneously de- 5 termining the accuracyiof tuning thereto 'by inspection 'of the "variations of :the tube shadow iangle.

'As already mentioned in connection-With Figs. 1 and2, the broad principles involvi-ngthe-utilization o'f'an electron ray tube as a tuningscale index' needrnot be'limited byspec'ificrmechanical details. Thus, the apparatusof FigqBrmayberead- 'ily modified soithat rduring rotation of control 4 5, a straight calibratedscale is displaced :in front of the fixed electron tube I4, instead of *arcuate "scale 43. nsin Fi-gihan index'linetl (optional) isproVided-upon the face-of tube 'M for precision scale reading.

"In Fig. :4 there is illustrated 'on electron ray tube i l-as described-in connection with Figs. '1, 2 and and an opaque shield 55 which maybe positioned over-the tube face so that only the region immediately surrounding the angular shadow of-thetube is visible. As-shown, electron raytdbe contains a-fiuourescent screen 52, luminous except for an angular shadow, as previously described, and a small, circular cap '53 for shielding straylight from the tube filament (not shown). The shield plate 55 shown displaced from the tube for clarity comprises essentially --a circular disk having a plurality of integral tabs 56 extending therefrom. Tabs 56 serve to removably'secure shield 55 tothe face of electron ray tube l5.

Two small angular openings 6| are provided in the'shield plate 5.5 and are oriented relative to the face of tube .I4 so that the variable angle shadow appearing onfiuorescentscreen 52, when tube M is energized, is visible therethrough. IIhe angular shadow is preferably symmetrically oriented with respect to index strip 62, formed by the shield element between openings 6!. The common vertex 63 of angular openings 6! is ,displaced from the center of shield .55 by a small amount andis above the edge of light shield '53.

senses The combination of shield plate 55. and tube [4} as illustrated in Fig. 4' provides a compact index assembly for use in apparatus; as in Figs. 1,2 and ,3. The index strip functions as index line 31 mentioned in connection'with Figs. 1 and The electron ray tube index of this invention maybe utilized upon electronic apparatus wherever a scale indication is-required in addition to avisual indication of a particular circuit condi- It is evident that electron ray tube l4 may be of conventional construction, or of a modified construction for adaptation to a particular system.

miniature) envelope. In order to increase effectiveness, the cathode structure of the electron ray tube maybe displaced from its normal central position and a non-symmetrical target electrode associated. therewith to provide a maximum size angular shadow.

In view of these and other possible modifications of the specific disclosures hereinabove set forth which may now become apparent to those skilled in the art, it is preferred that the spirit and scope of the present invention be limited solely by the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. A. tuning system for a radio receiver comprising, a calibrated scale, an electron ray tube electrically coupled to said radio receiver and presenting a variable angle shadow, the angle of said shadow being a minimum when said radio is accurately tuned to a received signal, means for supporting said electron ray tube adjacent to said calibrated scale, said means being arranged whereby a line of sight directed axially of said tube substantially includes the vertex of said variable angle shadow and said calibrated scale, said vertex of said variable angle shadow thereby providing a visual index for said calibrated scale, and means operative during the tuning of said radio receiver for displacing said electron ray tube along said calibrated scale.

2. A tuning system for a radio receiver comprising, a substantially straight calibrated scale, an electron ray tube electrically coupled to said radio receiver and presenting a variable angle shadow, the angle of said shadow being a minimum when said radio is accurately tuned to a received signal, a carriage supporting said electron ray tube adjacent said straight scale and arranged whereby a line of sight directed axially of said tube substantially includes the vertex of said shadow angle and an edge of said straight calibrated scale, said vertex of said variable angle shadow thereby providing a visual index for said straight scale, and means operative during the tuning of said radio receiver for displacing said electron ray tube supporting carriage parallel to said straight scale.

3. A tuning system for a radio receiver comprising, a scale, an electron ray tube electrically coupled to said radio receiver and presenting a variable angle shadow, said scale and said electron ray tube being relatively movable, a shield positioned over the face of said electron ray tube, two substantially angular openings in said shield separated by an index strip, said angular openings having a common vertex, saidvariable angle shadow being visible through said openings, said electron ray tube and said shield being disposed relative to said scale whereby said common vertex and said index strip together provide an index for said scale.

' 4. An indicating system for electrical apparatus comprising, a scale bearing markings thereon and an electron ray tube presenting a variable angle shadow indicative of an electrical characteristic of said apparatus, said electron ray tube and said scale being arranged for predetermined relative movement throughout which said scale and said electron ray tube remain adjacently disposed, said variable angle shadow thereby providing an index for said scale, said scale and said electron ray tube being further arranged whereby a line of sight substantially axial of said electron ray tube and directs-d toward said variable angle shadow extends substantially normal to the plane of and in intersecting relationship with said markings of Said scale.

5. A tuning system for a radio receiver comprising, a scale having markings related to the frequency range tunable by said receiver, an electron ray tube electrically coupled to said radio receiver and presenting a variable angle shadow, the angle of said shadow being a minimum when said receiver is accurately tuned to a received signal, index means disposed on the face of said electron ray tube substantially bisecting said variable angle shadow, means for supporting said electron ray tube behind and closely adjacent to said scale and arranged whereby on a line of sight axial of said electron ray tube the vertex of said variable angle shadow and said index means together indicate on said scale the frequency to which said radio receiver is tuned, and means operative during the tuning of said radio receiver for causing relative displacement of said electron ray tube and said scale while retaining the aforesaid adjacent relationship therebetween.

6. An indicating system for electrical apparatus comprising a calibrated arcuate scale, an.

electron ray tube in circuit with said apparatus and presenting an angular shadow variable in accordance with an electrical characteristic of said apparatus, means for supporting said electron ray tube adjacent to the calibrations of said arcuate scale whereby the vertex of said angular shadow is directed toward and provides a visual index for said calibrated scale and a line of sight axial of said electron ray tube, including said vertex, intersects the calibrations of said scale, and means operative during predetermined adjustment of said electrical apparatus for causing rotation of said arcuate scale while maintain ing the aforesaid relationship of said scale to said electron ray tube, said electron ray tube being substantially fixed and displaced radially of the center of rotation of said arcuate scale.

'7. An indicating system for electrical apparatus comprising, a scale bearing predetermined markings thereon, an electron ray tube electrically coupled to said apparatus and presenting an angular shadow variable in accordance with an electrical characteristic of said apparatus, said scale and said electron tube being relatively movable, a shield positioned over the face of said electron tube, said shield having an angular of sight axial-- of said tube, includingvthe-wertex :ai an nl r n n b ing arra ed to intersect said scale markings.

-8. -An indicating :system for electrical Zapparatus comprising, a calibrated scale, an electron raytube in'circuit with said apparatus and presenting an angular shadow variable in accordance .with an electrical characteristic of said apparatus, said electron ray tube having a ,line marked on i. the face -thereof substantially bisecting the-angle ofsaid shadow, imeansfor supportingsaid electron ray-' tube behind and directly adjacentto said calibrated :scale,v the longitudinal axis ofsaid electron ray tube extending substan- .tially through the calibrations ,on said scale,

aforesaid relationship betweensaid tube longitudinal axis andsaid calibrationsonsaid scale,

said variable angle shadow beihgpointed toward. and .thereby providing a visual index for the: calibrations on said scale, said line on the face: af-said electron, ray tube being visible at the edge: of said scalevand thereby providing means for taking accurate readings of the calibrations on saidscale.

.JOSEPH' WEINGAR'IEN.

REFERENCES CITED The following references are of record in tlm 'file I of this patent:

UNITED STATES PATENTS Number 'Name Date .2,1'24,023 'Albright et a1. July '19, 1938 12,160,270 Kenney May 30, 1939 .2;1 76-,'6'73 Krause Oct. 1'7,- 1939 12,19,41-69 -Metcalfe Mar. 19, 1940 v2 ,3 4="1,97'Z LLieshant May 2,49% 

